It is known in the art to use ultrasound imaging systems to acquire internal images of a body, such as an anatomical body, in order to plan or perform a medical procedure, be it diagnostic, therapeutic or surgical. There are several advantages to using ultrasound imaging systems over other imaging systems. For example, ultrasound imaging systems tend to be less intrusive on the body and do not expose the patient to large amounts of radiation or dyes. In addition, ultrasound imaging systems tend to be less expensive to purchase. Ultrasound imaging systems also tend to be less expensive to operate because there are fewer personnel involved, it is not necessary to keep the patient stable, and the ultrasound images need not be "pre-acquired", but can be acquired during the medical procedure.
The principal advantage of imaging systems in general is the ability to visualize internal regions of a patient and to guide medical instruments or probes within the body of a patient without making large incisions into the body of the patient. Making smaller incisions into the body of the patient decreases the risk for the patient and also the duration of the patient's hospital stay.
However, to effectively use images as a navigational aid during a procedure on the patient, the images being acquired by the ultrasound imaging transducer must be displayed in a clear, accurate and user-friendly manner. Only then can the medical practitioner easily visualize the internal region of the body.
In the past, the images acquired by an ultrasound imaging transducer could only be viewed from one perspective or view, namely from the perspective of the ultrasound imaging transducer which was acquiring the images. While the imaging transducer could be moved around the body to acquire images from different perspectives or views, it was not possible to acquire images from the perspective or view of the instrument. The medical practitioner would be left with the task of extrapolating the position, orientation and course of the instrument in the body from the images on the display.
In addition, the position of the instrument in prior art systems is generally not easily seen on the acquired images. To improve visibility of the instrument, it was often necessary to place an ultrasound tracking transducer on the instrument. The ultrasound tracking transducer would receive the ultrasound signals emitted by the ultrasound imaging transducer and provide a "blip" to represent the instrument on the images. But this would require modified instruments and additional cost.
Therefore, the prior art has suffered from several disadvantages. In particular, the prior art systems could only generate and display clear ultrasound images from one perspective or view, namely from the perspective or view of the ultrasound imaging transducer. However, this view provides a poor navigational tool for a medical practitioner at least because the medical practitioner cannot easily visualize the course of the instrument in the body.
In addition, most of the prior art systems require that a tracking transducer of some type be located on the probe or medical instrument which was inserted into the body of the patient. Modified instruments incorporating tracking transducers must be used.
Accordingly, there has been a need in the art for an alternative method and system for accurately, efficiently and robustly presenting the images acquired from an ultrasound imaging transducer. In addition, there is a need for a system which does not require the medical instruments to have ultrasound tracking transducers which enter the body.